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Chpt 8-1
ENERGY & LIFE
Energy in most foods comes from the Sun.
Autotrophs – Organisms that make their own food (ex) Plants
Heterotrophs – Organisms that eat other organisms. (ex) Animals
During digestion, complex carbohydrates are broken down to the monosaccharide glucose.
At the small intestine, Glucose diffuses into the blood and is carried into the cells.
Glucose enters the mitochondria and is converted to ATP, a usable energy molecule for the cell.
ATP – A high energy molecule in cells that stores and releases energy from glucose.
ADP – A lower energy molecule used to create ATP.
ATP CREATION AND USE
o Glucose from blood enters cell and goes into Mitochondria.
o ADP enters and stores energy of Glucose in bond between 2nd and 3rd Phosphate A-T-P-P==P
o ATP enters cytoplasm where it is quickly used in chemical reactions, becoming ADP.
o Cycle repeats.
Chpt 8-2 & 8-3
PHOTOSYNTHESIS
Photosynthesis – process of converting light, water and CO2 into O2 and carbohydrates.
light
PHOTOSYNTHESIS = 6 CO2 + 6 H2O C6H12O6 + 6 O2 “666” in every term.
Chloroplasts – Organelles in cells where photosynthesis occurs.
Thylakoids – photosynthetic saclike membranes arranged in stacks.
Grana – stacks of thylakoids
Lumen – Inside part of Thylakoid.
Stroma – Area outside thylakoids.
Pigments – Light absorbing molecules found in chloroplasts. (ex.) Chlorophyll
Photosystems – Groups of pigments.
Two Stages of Photosynthesis
I.
Light Dependent Reaction
• Occurs along Thylakoid membrane.
• Releases O2 into the air.
• Creates high energy molecules (ATP & NADPH) for Sugar creation.
II.
Light Excites electrons in PS II chlorophyll, increasing their energy and leaving their orbits
Electrons move along Electron Transport Chain drawing H+ from Stroma into Lumen
H2O is broken by enzymes releasing O2, replacing electrons in PS II storing H+ ions in lumen
Weakened electrons in ETC replace excited electrons that left PS I chlorophyll
PS I electrons and an H + are carried by NADP+ forming high energy NADPH.
High concentration of H+ in Lumen diffuse through ATP Synthase creating ATP.
Light Independent / Dark Reaction (Calvin Cycle TURNS 2X )
• Occurs in Stroma.
• Sugars (Carbohydrates) are created from CO2 and existing 5 carbon molecules.
• CO2 contributes a Carbon and Oxygen to C6h12o6 formation.
• NADPH donates electrons (energy) and Hydrogen.
• ATP donates energy.
Remaining Carbon molecules repeat cycle.
FACTORS AFFECTING PHOTOSYNTHESIS
Water Shortage – Can slow down or stop Photosynthesis. Some desert pants have waxy coating
to reduce water loss.
Temperature – Photosynthesis depends on enzymes that work best between 0C-35C (32F-95F)
Light Intensity – Increase or decrease of light will increase or decrease Photosynthesis.
LIGHT DEPENDENT REACTION
CALVIN CYCLE (LIGHT INDEPENDENT or DARK REACTION)